Karyotype Analysis: Categorisation of Chromosomes and Chromosomal Abnormalities

Question 1

Acquired

Answer 1

A genetic change associated with a neoplastic or cancer disease process. Contrast with
congenital/ constitutional

Question 2

Aneuploidy

Answer 2

Normally, an individual has two of each chromosome. Aneuploidy means that there are too
many copies of a particular chromosome, i.e. three or more chromosomes. This condition is usually fatal
with the exception of X chromosomes, where X- inactivation greatly reduces the effect

Question 3

Centromere

Answer 3

Region in the chromosome that separates the long arm from the short arm, consisting of
hereochromatin . Important for separation of chromatids in mitosis and meiosis

Question 4

Chromatin

Answer 4

Chromosome material (DNA + packaging proteins). Euchromatin: actively transcribed
regions; Heterochromatin: contains many repeats and no functional genes; structural function.
Congenital/constitutional: That which is from birth. Contrast with acquired.

Question 5

Gynecomastia

Answer 5

Excessive development of the male mammary gland

Question 6

Hypogonadism

Answer 6

Characterized by abnormally decreased functional activity of the gonads (ovary or
testis), with retardation of growth

Question 7

Karyotype

Answer 7

A systemized array of the chromosomes of a single cell prepared either by drawing or by
photography, with the extension in meaning that the chromosomes of a single cell can typify the
chromosomes of an individual or even a species

Question 8

Mosaicism

Answer 8

Two or more cell lines with different chromosome complements, in the same individual and
originating from the same zygote

Question 9

Metaphase

Answer 9

One of the stages of cell division (prophase, metaphase, anaphase and telophase). Cell
division is accomplished relatively quickly and cells spend most their time in the ‘interphase’ stage of the
cell cycle in which chromosomes are de-condensed and typically referred to as chromatin or chromatin
fibers. Such chromatin is difficult to see within the nucleus. In metaphase, the chromatin is condensed
into chromosomes, which are easily observed with the light microscope

Question 10

Paint

Answer 10

The Paint method is a variation of Fluorescence In-Situ Hybridization (FISH). There are dyes that
are chromosome specific, or even specific for certain parts of one chromosome. By painting
chromosomes with different dyes one can identify translocations, inversions and marker chromosomes

Question 11

Translocation

Answer 11

A translocation between two chromosomes means that part of one chromosome, or an
entire chromosome, has been attached to another chromosome. Translocations can occur between two or
more chromosomes. The translocation is called Robertsonian if it involves an end to end fusion of two
chromosomes. A translocation between, for example, chromosomes 9 and 22 is written as t(9,22)

Question 12

X- inactivation

Answer 12

The irreversible shut-down of genes on one X chromosome in somatic cells in human
females (and other mammals)